Class a: All alpha proteins [46456] (226 folds) |
Fold a.4: DNA/RNA-binding 3-helical bundle [46688] (14 superfamilies) core: 3-helices; bundle, closed or partly opened, right-handed twist; up-and down |
Superfamily a.4.13: Sigma3 and sigma4 domains of RNA polymerase sigma factors [88659] (3 families) |
a.4.13.1: Sigma3 domain [88660] (3 proteins) |
a.4.13.2: Sigma4 domain [88665] (4 proteins) |
a.4.13.3: YlxM/p13-like [109706] (2 proteins) Pfam 04297; UPF0122 structural and detectable sequence similarity to Sigma4 domain; contains extra C-terminal all-alpha oligomerization subdomain; forms different, helix-swapped dimers |
Timeline for Superfamily a.4.13: Sigma3 and sigma4 domains of RNA polymerase sigma factors: